> It's remarkable how institutions (the school psychologist in your case) often re-inflict the trauma that is going on at home. It's their job to protect the child, but often they do the opposite, and it's worth asking why. I experienced this myself, though in a very different context—everyone's story is unique of course.

I think the simplest explanation here is Sturgeon's law: 90% of everything is crud. This goes for members of institutions as well, even if they aren't overworked, underpaid, and undertrained as so many are.

On top of that, abusers are often charming and highly skilled liars and manipulators. To get away with it for an extended period of time it is necessary to convince the victims that institutions won't help them, so performing abuse in front of a representative of the institution can be a ploy to reinforce their power. If the school psychologist had been likely to challenge the abusers, they likely would have picked a different authority figure (teacher, principal, &c.).